How does a Linux operating system rival a thousand miles away

Linux, as an open-source operating system, is absolutely not secure for other systems. But sometimes there will still be some minor problems. Next we will look at how to solve the problems. At the just-concluded Pwn2Own conference, almost all systems were ridiculed by hackers, hackers proved by their actions that the manufacturers did nothing ".

However, hackers belong to hackers. the Linux operating system is usually a relatively secure system. Of course, many friends may encounter the problem of server hacking. Related materials are collected and sorted out here, here I have found a solution for Linux operating system server hacking. I hope you will see a lot of GAINS.

If you have installed all the correct patches, have tested firewalls, and have activated Advanced Intrusion Detection Systems at multiple levels, then you will be hacked only in one situation, that is, you are too lazy to do what to do, such as installing the latest BIND patch.

It is really embarrassing to be hacked without being careful. More seriously, some script moles will download some well-known "rootkits" or popular spying tools, these occupy your CPU, memory, data, and bandwidth. Where did these bad guys start? This starts with rootkit.

A rootkit is actually a software package that hackers use to provide themselves with root-level access permissions to your machine. Once the hacker can access your machine as root, everything is done. The only thing you can do is to back up your data with the fastest efficiency, clear the hard disk, and reinstall the operating system. In any case, it is not easy to restore your machine once it is taken over by someone.

Can you trust your ps command?

The first trick to identify rootkit is to run the ps command. Everything may seem normal to you. The figure below shows an example of ps command output. The real problem is, "Is everything really normal ?" A common trick for hackers is to replace the ps command, and the ps on the replace will not show illegal programs running on your machine. To test files, check the size of your ps file, which is usually located in/bin/ps. In our Linux operating system, it is about 60 kb. I recently met a ps Program replaced by rootkit, which is about 12 kb in size.

Another obvious scam is to link the root command history file to/dev/null. This command history file is used to track and record commands used by a user after logging on to a Linux machine. Hackers redirect your history files to/dev/null so that you cannot see the commands they have input.

You can access your history file by typing history at the shell prompt. If you find that you are using the history command and it does not appear in the list of commands you have used before, you should take a look at your ~ /. Bash_history file. If the file is empty, execute an ls-l ~ /. Bash_history command. After you execute the preceding command, you will see the following output:

-Rw ------- 1 jd 13829 Oct 10/home/jd/. bash_history

Alternatively, you may see output similar to the following: lrwxrwxrwx 1 jd 9 Oct 1019:40/home/jd/. bash_history->/dev/null

If you see the second one, it indicates this. The bash_history file has been redirected to/dev/null. This is a fatal message. Now, you can immediately disconnect your machine from the Internet, back up your data as much as possible, and reinstall the system.

To solve the problem of Linux operating system server hacking, you need to find an unknown user account:

It is wise to first check whether there are unknown user accounts when you plan to perform a test on your Linux operating system machine. When you log on to your Linux server the next time, run the following command:

Grep: x: 0:/etc/passwd

There is only one line. I will emphasize that in a standard Linux installation, the grep command should return only one line, similar to the following:

Root: x: 0: 0: root:/bin/bash

If your system returns more than one row after the previous grep command is typed, the problem may occur. The UID of only one user should be 0. If the returned result of the grep command exceeds one row, more than one user will be returned. Seriously, the above are some good basic methods for discovering hacker behavior. However, these techniques cannot constitute sufficient security, and their depth and breadth are far from the intrusion detection system mentioned in the article.

The above is a small point of knowledge about the solution to linux operating system server hacking. I believe that some actual "economic" behaviors will be ruled out, and the elites of many hackers will not be able to patronize our servers.